One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(5,6,11,16)(7,17,21,48)(8,22,26,54)(9,27,31,46)(10,32,29,15)(12,34,37,19)(13,38,41,25)(14,42,44,30)(18,49,51,68)(20,52,33,43)(23,47,56,66)(24,57,60,40)(28,45,61,36)(35,62,63,55)(39,58,65,50)(53,64,67,59)(5,7,11,21)(6,12,16,37)(8,23,26,56)(9,28,31,61)(10,33,29,20)(13,39,41,65)(14,43,44,52)(15,45,32,36)(17,46,48,27)(18,38,51,25)(19,42,34,30)(22,35,54,63)(24,58,60,50)(40,66,57,47)(49,67,68,53)(55,64,62,59)(2,4)(5,8,9,24,29,38,42,64,11,26,31,60,10,25,30,59)(6,13,14,40,32,54,46,67,16,41,44,57,15,22,27,53)(7,18,19,50,33,56,61,62,21,51,34,58,20,23,28,55)(12,35,17,47,45,65,52,68,37,63,48,66,36,39,43,49)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.